Local and anisotropic excitation of surface plasmon polaritons by semiconductor nanowires

We demonstrate a novel functionality of semiconductor nanowires as local sources for surface plasmon polaritons (SPPs). Photoexcited semiconductor nanowires decay non-radiatively exciting SPPs when they are on top of a metallic surface. We have investigated the anisotropic excitation of SPPs by nanowires by placing individual InP nanowires inside gold bullseye gratings. The gratings serve to couple SPPs to free space radiation that is detected with a scanning confocal microscope. The circular geometry of the grating allows to conclude that SPPs are preferentially generated in the direction along the nanowire axis.